Storm-Track Response to SST Fronts in the Northwestern Pacific Region in an AGCM

• Published in: Journal of climate Vol. 30; no. 3; pp. 1081 - 1102
• Main Authors: Kuwano-Yoshida, Akira, Minobe, Shoshiro
• Format: Journal Article
• Language: English
• Published: Boston American Meteorological Society 01.02.2017
• Subjects: Anomalies; Atmospheric circulation; Atmospheric circulation models; Atmospheric precipitations; Circulation; Coastal environments; Cold; Condensation; Cyclone development; Cyclones; Diagnostic systems; Earth science; Experiments; Fronts; General circulation; General circulation models; Growth rate; Heat transfer; Jet stream; Jet streams (meteorology); Laboratories; Latent heat; Latent heat release; Mathematical models; Moisture; Moisture flux; Precipitation; Pressure; Rivers; Sea level; Sea level pressure; Sea surface; Sea surface temperature; SPECIAL Climate and Frontal Air-Sea Interaction COLLECTION; Storms; Stream discharge; Stream flow; Studies; Surface pressure; Surface temperature; Temperature effects; Troposphere; Upper troposphere; Wind; Winter; Japan
• ISSN: 0894-8755; 1520-0442
• DOI: 10.1175/jcli-d-16-0331.1

The storm-track response to sea surface temperature (SST) fronts in the northwestern Pacific region is investigated using an atmospheric general circulation model with a 50-km horizontal resolution. The following two experiments are conducted: one with 0.258 daily SST data (CNTL) and the other with smoothed SSTs over an area covering SST fronts associated with the Kuroshio, the Kuroshio Extension, the Oyashio, and the subpolar front (SMTHK). The storm track estimated from the local deepening rate of surface pressure (LDR) exhibits a prominent peak in this region in CNTL in January, whereas the storm-track peak weakens and moves eastward in SMTHK. Storm-track differences between CNTL and SMTHK are only found in explosive deepening events with LDR larger than 1 hPa h−1. A diagnostic equation of LDR suggests that latent heat release associated with large-scale condensation contributes to the storm-track enhancement. The SST fronts also affect the large-scale atmospheric circulation over the northeastern Pacific Ocean. The jet stream in the upper troposphere tends to meander northward, which is associated with positive sea level pressure (SLP) anomalies in CNTL, whereas the jet stream flows zonally in SMTHK. A composite analysis for the northwestern Pacific SLP anomaly suggests that frequent explosive cyclone development in the northwestern Pacific in CNTL causes downstream positive SLP anomalies over the Gulf of Alaska. Cyclones in SMTHK developing over the northeastern Pacific enhance the moisture flux along the west coast of North America, increasing precipitation in that region.